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Best Way To Insulate A New House In Pennsylvania

January 29th, 2024

7 min read

By Alexis Dingeldein

When you're building a new house, you have a lot of details to consider. You have to think about everything from the floor plan to the paint colors. As much fun as interior design planning can be, you also have to think practically about the bones of your house. And one of those essential bones is your insulation.

South Central Services has insulated hundreds of homes with spray foam insulation. Our team works with both new and existing homes. While we're happy to install spray foam in attics, basements, and crawl spaces as a retrofit application, new houses are one of the best applications for spray foam insulation. When a house is brand-new, we can completely handle the insulation package for that home and ensure the lowest possible energy bills.

This article will share our best practices for insulating new construction homes in southern Pennsylvania and the surrounding states. By the end, you will understand:

  • The steps to completely insulating a brand new home
  • Factors that influence the choice of insulation

Don't have time to read right now? Check out everything you need to know at a glance.

Steps To Insulating A New House

One of the best parts about building a new home is the opportunity to insulate everywhere. After a house is built, some places can only be accessed again by demolishing parts of your home. Other areas can never be reaccessed, even with remodeling.

When we insulate a new construction home and handle the entire insulation package, these are the areas we are sure to insulate.

1. Underslab Insulation For A Monolithic Seal

One area of a new home that we can insulate is the home's foundation. For underslab insulation, we install 2 to 4 inches of closed cell spray foam, usually sprayed directly down to the stones. This layer of spray foam creates an airtight seal and a vapor barrier. The insulation also prevents radon transfer.

The foundation of a house, or underslab, insulated with closed cell spray foam.

The airtight seal helps to create a seamless thermal envelope, also known as a monolithic seal. Without underslab insulation, you can get thermal transfer through your foundation.

Since your foundation is underground, it faces excess moisture from the surrounding dirt. The vapor barrier of closed cell spray foam prevents the potential of condensation on your slab.

Another concern underground is radon transfer. A layer of closed cell spray foam on your foundation can help mitigate radon. Without this insulation, radon levels can be elevated.

2. Crawl Space Encapsulation Or Basement Insulation For Your Thermal Envelope

Every house is different. Some have just a basement. Others have a crawl space. Still others have some combination of the two. How we insulate this below-grade area will depend on what it looks like and your intentions for the space.

For homes with just a crawl space, South Central Services encapsulates with plastic sheathing and closed cell spray foam. Encapsulation adds the crawl space into your thermal envelope and keeps the space clean and dry.

This crawl space in Adams County, Pennsylvania, was encapsulated. This included a vapor barrier on the floor and closed cell spray foam on the walls.

If your home has just a basement, there are two potential options for insulation. Homeowners who want a finished basement with usable living space should have their basement walls insulated with closed cell spray foam.

If the basement won't be used as living space, the basement ceiling can be insulated instead. In these cases, our crew often uses open cell spray foam as a sound barrier between floors. Either the basement walls or ceiling must be insulated to meet code compliance.

The basement of a new construction home where the basement walls are insulated with spray foam.

Our team can put together a specific solution for homes with a combination of a basement and crawl space. That solution will likely involve closed cell spray foam, which is approved for below-grade applications.

3. Exterior Wall Insulation For Maximum Energy Efficiency

Your exterior wall insulation plays a vital role in managing your home's temperature. Exterior walls make up a significant portion of the thermal envelope. You can think of the thermal envelope as the barrier between your home and the outside. Depending on the design of your house, your thermal envelope may be shaped like a cube or more like a cube with a pyramid on top.

Every place in your thermal envelope should be air-sealed. An airtight seal prevents heat from transferring through convection. Traditional insulations only stop heat through conduction. You can stop conduction and convection heat by using an insulation like spray foam.

A spray foam insulation crew member shaving excess open cell spray foam from the walls of a new construction home.

Your climate zone and building materials will impact which type of spray foam insulation belongs in your walls. As long as the exterior walls are above-grade, open cell spray foam is usually an option for homes in Pennsylvania. No matter what, closed cell spray foam is an option for exterior walls.

4. Interior Wall Insulation For Sound Control

The goal of interior wall insulation is entirely different from exterior walls. Your interior walls don't need to stop heat transfer. The walls inside your home form barriers between rooms, not climates. The main purpose of insulation in interior walls is to prevent sound transfer.

Open cell spray foam is a product that offers sound attenuation, but it is too expensive to justify using in interior walls. It also provides more insulating performance than interior walls need.

For new construction homes, we recommend batt insulation in interior walls.

The differences between fiberglass, rockwool, and cotton are not measurable for this application. Any batt insulation will work well.

Batt insulation is sometimes installed in the exterior walls of new construction homes to save money. We do not recommend batt insulation for this application because it cannot stop convection heat transfer. If you want batt insulation in your exterior walls, we recommend a hybrid insulation method. The hybrid method combines spray foam and batt insulation.

5. Attic Insulation For Your Thermal Envelope

After your foundation, basement, and walls have all been insulated, you need to insulate your attic. Attic insulation is chronically overlooked in our service area, especially in new construction homes. Attics are often an afterthought. These spaces either have no insulation at all or have an insufficient amount.

Your attic is part of your thermal envelope. Depending on how you'd like to use your attic space, you can choose between a vented and an unvented attic. If your attic is meant for storage and doesn't need conditioned air, you can insulate the attic floor and leave the attic space vented.

A spray foam insulation contractor insulating a ceiling with open cell spray foam.

If you need conditioned air in the attic, you'll insulate the roof and gables. Attics with HVAC equipment, important storage, or living space should be unvented. Sealing off the attic prevents random air from leaking inside and disrupting the temperature or humidity.

The most common attic insulation we see in southern PA is batt or blown-in insulation. While these products can slow conductive heat transfer at sufficient amounts, they do not offer an airtight seal. They also require regular maintenance.

We recommend open cell or closed cell spray foam insulation for attics.

Whether creating a vented storage space or an unvented living space, spray foam insulation will make for an airtight seal. This airtight seal finishes off a flawless thermal envelope and prevents as much air leakage as possible.

Every House Is Different, But Most Building Principles Stay The Same.

While this article explains the best practices for insulating new construction homes, there is no one-size-fits-all approach to insulation. It would be irresponsible of us to imply that there was. Ultimately, every insulation and building material has different properties that work together differently in different situations.

For insulation to be most effective, several factors have to be considered. Let's examine these factors in more detail.

1. Consider Your Climate Zone.

Insulation does not operate in a vacuum. The role of insulation is to stop heat transfer. In the summer, insulation fights to keep your house cool. In the winter, insulation does its best to keep your expensive heating inside.

Homes in southern Pennsylvania experience four distinct seasons. The disparity between our inside and outside temperatures is more extreme than in other parts of the United States. We have significantly higher energy bills if our homes have inadequate insulation.

What climate zone do you live in? Check out this climate zone map from the International Code Council.

Homeowners in milder climates who don't have distinct seasons or a variety of seasonal clothes in their closets don't have to be as concerned with high quality insulation. However, having the best insulation certainly won't hurt and can even help with other problems like indoor air quality.

The weather patterns will influence what features your insulation needs. For example, customers in our service area almost always need vapor barriers. Even if their property or project doesn't need a vapor barrier, it must be discussed based on our climate. The further south you travel, the less often vapor barriers enter the discussion for home insulation.

2. Consider Your Home Design.

Did you know how a house is constructed can change how air leaks from it? When South Central Services insulates a new home, we take the time to air-seal every possible crack and crevice where air could infiltrate.

A row of 2x4 planks in a new construction home.

Even when 2x4 beams are placed side by side, air can infiltrate. The actual construction of your home can mean you need more or less air-sealing.

3. Consider Your Building Materials.

Every building material conducts heat differently. Metal, for example, is an excellent conductor of heat. Because materials react to weather and heat differently, they can influence the insulation material you use.

Imagine a metal building insulated with fiberglass batt insulation. In the wrong climate zone, metal may condense vapor from the air. The water that forms on the metal would come into contact with the insulation. While fiberglass batt insulation is mold-resistant on paper, the insulation could create a breeding ground for mildew or mold.

For spray foam insulation, the type of building material can be an essential consideration. In our climate zone, Climate Zone 5, open cell spray foam can only be installed against wood and closed cell spray foam. The adhesion of spray foam is vital to its performance. The properties of open cell make adhesion to metal, concrete, or stone an unwise choice.

What Makes An Insulation The Best Choice?

When choosing insulations for your new home, you need to consider what the area of your home needs, what the product offers, and what your budget is. You should not insulate every area of your home with the same insulation product because different parts of your home have different needs.

Let's say your home is built from wood and has an attic, crawl space, and two floors of main living space. You will likely use about three insulation products to insulate your home.

In your exterior walls, you may use open cell spray foam. The choice of open cell will save you money compared to closed cell spray foam, but your walls will still offer the airtight seal you need.

In your interior walls and between floors, you may use batt insulation. Whether the batts are fiberglass, cotton, or rockwool does not matter. While batt insulation doesn't offer excellent performance, it does muffle sound transfer. Open cell spray foam can also muffle sounds, but would be more expensive to install. Your interior walls don't need the same performance as your exterior ones.

In your crawl space and attic, you may use closed cell spray foam. Your crawl space must have closed cell because it offers a necessary vapor barrier that no other insulation can provide. As for your attic, you may opt for closed cell to install on the roof. This roof insulation adds your attic to the conditioned space of your home, making it possible to use as living space. Closed cell spray foam is more expensive, but less insulation must be installed in the roofline, making finishing the attic an easier task.

The Bottom Line About How You Insulate Your New Home

No matter which insulations you're considering, South Central Services will always advocate for an airtight seal in your thermal envelope. Since you're building a new home, you have the chance to put the best performing insulation in your exterior walls and other thermal envelope surfaces.

Some insulation is better than no insulation, and premium products are better than budget ones. To optimize your home for maximum energy efficiency, insulate every area where air can leak with the appropriate spray foam insulation.

Now that you know the best way to insulate your new home, your next step is to find an insulation contractor. By the time your home is being framed, you should have selected a contractor to install your insulation. If you live in our service area, find out why homeowners trust us to insulate their new homes.

Want to learn more about your insulation options? Discover the pros and cons of these insulations.

Alexis Dingeldein

Alexis has been fascinated by spray foam insulation since 2018. When she isn’t thinking about insulation, Alexis is geeking out over storytelling and spreadsheets.